Algae Research in Full Bloom at NREL

Oct 05, 2010 - Heather Lammers - NREL Newsroom

In a test tube, vibrant green microalgae look fragile,
but in reality getting them to spill their lipid secrets
to make renewable fuels is a challenge — one that
researchers at the U.S. Department of Energy's (DOE)
National Renewable Energy Laboratory are tackling, again.

From 1978 to 1996, DOE funded NREL's study of microalgae
under the Aquatic Species Program. During that time,
3,000 algae strains were isolated from various aquatic
habitats. Roughly 50 caught the attention of researchers
for their potential use in producing transportation fuels.

Then in 1996, the price of oil bottomed out at roughly
$20 a barrel. The estimated cost of algae oil at the
time was about $80 a barrel. With those price factors
and other budget pressures, DOE stopped funding the Aquatic
Species Program. Algae strains were sent to the University
of Hawaii for safekeeping and the NREL team summarized
nearly 20 years of research in the program's Close Out
Report.

Fast forward 10 years and the Energy Independence and Security Act of 2007
(EISA) is passed by Congress. The 2007 law required that the U.S. produce
and use 36 billion gallons of renewable fuels by 2022. EISA capped the use
of starch based ethanol at 15 billion gallons and called for the remainder
to be made up by "advanced biofuels"— basically anything
else.

Because of its past research, NREL was ahead of the
curve. In 2006 an NREL research team began seeking new
funding for algae research. "We started another
aquatic species program but it is really quite different
from the first," said NREL Principal Group Manager
Al Darzins. "And we have surpassed the old aquatic
species program in terms of funding."

In a few short years, the team raised more than $8 million.
One of the goals was to diversify program funding said
Darzins. DOE is again in the mix, but so is the Department
of Defense (for work with the U.S. Air Force Office of
Scientific Research) and companies like Chevron with
whom NREL has Cooperative Research and Development Agreements.

NREL used some funding to retrace work in the old program
by bio-prospecting for new strains, but thanks to new
technology, the work goes a lot faster.

"We've accumulated almost 400 different algal strains
from differing environments — freshwater, brackish
and saline," Darzins said. "Today we have higher
throughput devices that allow us to process samples very
quickly. Think about it like using tweezers — although
it's a little more complicated than that. We can actually
sort and pick out, at will, individual algae from the
water sample and get a pure culture of a single strain
of algae."

Once samples are collected, NREL is focused on understanding
the biology of the organisms. "If you don't understand
the biology and how to grow them, how are you ever going
to grow them at a large scale and control them?" Darzins
said.

NREL chose a strain of the algal species, Chlorella
vulgaris, as its model organism. Researchers are trying
to get a complete view of its molecular biology and biochemistry.
In their opinion, it's a good study subject because it
grows quickly and makes a lot of oil.

But, one of the hard parts of dealing with algae is
getting the oil out of the cells — this is especially
true with Chlorella vulgaris. "We typically use
some sort of solvent — but even that's not so easy
and the cell wall can resist it," Principal Research
Supervisor Phil Pienkos said. "NREL is working to
find enzymes that can help degrade the cell wall of algae
and allow the solvents access so we can more efficiently
extract the oil."

According to Pienkos, if an enzyme is found that can
easily break down the cell wall, it might be possible
to isolate the gene for that enzyme and engineer the
algae to produce that enzyme just before it is ready
to harvest.

"If you could induce the enzymes so that the cells
become weakened on their own then it's possible that
the cell could survive and you could separate out the
oil and return the cells into cultivation," Pienkos
said. "That would be a real cost savings."

"NREL is looking at the metabolic engineering of
algae but only to find out the fundamentals of how these
organisms tick," Darzins added. "We are not
growing genetically modified organisms outside the lab.
By using them only in the controlled laboratory setting,
we think it will tell us quite a bit."
To accelerate the deployment of advanced biofuels, President Obama and Secretary
of Energy Steven Chu announced the investment of $800 million in new research
on biofuels in the American Recovery and Renewal Act. The announcement included
funds for research, development and deployment of commercial algae-to-biofuels
processes. Algenol was awarded $25 million to pilot a photo-bioreactor algal
biofuel system — and NREL is working with this company to help them accelerate
commercial production.

"They have a unique technology using algae to convert
carbon dioxide (CO2) directly to ethanol," Pienkos
said. "Their photo bioreactor system allows them
to continuously produce ethanol so they don't have to
harvest algae."

NREL is working with Algenol on two fronts — a
techno economic and lifecycle analysis of their production
facility and evaluation of the algae for sensitivity
to components in the flue gases used to feed the algae.

"When most people do their small-scale work they
tend to use air mixed with pure CO2," said Pienkos. "When
they scale-up they have to think about using an industrial
source of CO2, which is made up of different components.
No one is sure if flue gas will have a long-term impact
on algae production."

Whether a company is striving to make ethanol, green
diesel or even jet fuel from algae, the key will be isolating
the right algae from the pool of thousands, if not hundreds
of thousands of available strains in the environment.
Sorting through water samples looking for the right candidate
for a project consumes lots of money. NREL is solving
that problem by using infrared light to sort out the
best oil-producing algae.

"The traditional method to measure the oil content
of algal biomass is very cumbersome," Researcher
Lieve Laurens said. "It takes a long time — up
to two days – and it uses lots of chemicals. We
are using near infrared spectroscopy to determine the
oil content in the algae in a matter of minutes."

The process works by shining a broad spectrum light,
with wavelengths ranging from the visible to the infrared
region of the spectrum, at the sample. Several different
detectors measure how much light is reflected versus
how much was absorbed by the sample. According to Laurens,
different molecules in the algal biomass will have different
absorption peaks showing a "fingerprint" for
the algae. That fingerprint, along with a mathematical
model, is then used to estimate the oil content of that
particular strain of algae.

The technique is non-destructive to the cell and, at
this point, seems to be species agnostic. "In this
case, we can scan the biomass and then continue doing
something else with it," Laurens said. This technique
has researchers pondering other possible applications. "For
example, we could use this technique to screen a large
number of algal strains in a culture collection in the
search for high oil producers without having to measure
the oil content using traditional methods."

Other plans are to apply these infrared methods to growing
cultures to see if researchers can do real-time monitoring
and determine when a culture is ready to be harvested.
In addition, there is an application for crop protection.

"In an outside open-pond system, it is likely that
other algae will land in the pond and try to out-compete
your species so this technique could be handy for monitoring
the health of your crop," Laurens said.

What Do You Make with Leftovers?
Once an algal strain is selected, cultivated and the oils are finally harvested,
there are leftovers which are referred to as residual biomass. The other
question NREL researchers are tackling is what to do with the leftovers.
Could they be used to make ethanol or biogas?

To make algae conversion a "two-fuels-for-the price
of one" winner, scientists have to understand what
makes up the algae biomass. The team is bringing NREL's
extensive knowledge in compositional analysis of biomass
to the table. "The expertise in the compositional
analysis group is a huge knowledge base so we don't have
to start completely from scratch when it comes to algae," Laurens
said. "There are certain methods we can use and
there are some things that will be unique and require
some creative solutions. For instance, the carbohydrates
in algae are very different compared with those found
in biomass like corn stover."

No matter the many new challenges NREL researchers face
when it comes to using algae for any variety transportation
fuels, the work could really pay off in the end.

"Algae has a lot of potential, and NREL has been
doing a good job of not subscribing to all of the hype," Darzins
said. "We have been a credible advisor to DOE, industry
and the general research community. Our message has been
that for algal biofuels the potential is huge — it
could be a game changer. But, the challenges are equally
as daunting — and boy, have we got our work cut
out for us."

Learn more about NREL's work in microalgal biofuels
or read the National Algal Biofuels Technology Roadmap.